Turbine-wheel.



PATENTE I D J. KARRER. D JULY l 1.908 TURBINE WHEEL.

APPLICATION FILED JAN. 15 1907. Fig.2

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JOSEF KARRER,

OF ZURICH, SWITZERLAND, ASSIGNOR TO THE FIRM OF MASCHINENFABRIKOERLIKON, OF OERLIKQN, NEAR ZURICH, SWITZERLAND.

TURBINE-WHEEL.

' Specification of Letters Patent.

Patented July 14, 1908.

Application filed January 15, 1907. Serial No. 352,377.

To all whom it may concern:

Be it known that I, JosEF KARRER, a citizen of'the Republic ofSwitzerland, residing at Zurich, in Switzerland, have invented certainnew and useful Improvements in Turbine-Wheels for- Steam or GasTurbines; and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains' to make and use the same, referencebeing had to the accompanying drawings, and to letters or figures ofreference marked thereon,'which form a part of this specification.

This invention relates to a turbine wheel for steam or gas turbines, theblading 'of which consists of blades and distance pieces, or of bladesalone,- inserted in dovetail shaped, or other undercut grooves. 1 Insuch a turbine wheel the blades and distance pieces or the blades or thedistance pieces alone, are riveted axially of the rotor. The object ofthis axial riveting is to obtain a more solid or rigid attachment of theblades than heretofore usual and to prevent the rotor groove walls attheir narrowest cross section breaking away.

In order that blades of considerable radial length may be efficientlysecured according to this invention in the bottom of .the undercutgroove may be out another groove into which the long blades extend andwherein they are secured by axial rivets.

The accompanying drawings show examples of constructional forms ofturbine wheels embodying this invention.

Figure 1 is a transverse section through a portion of a rotor andblades. 'Fig. 2 is a vertical longitudinal section. Figs. 3, 4, 5, and 6are views similar to Fig. 2, showing modifications of peripheral groovesin the rotor. Fig. 7 is a view similar to Fig. 2. Fig. 8 is a viewsimilar to Fig. 1 showing the manner of mounting the blades in rotorperiphery shown in section in Fig. 6.

Figs. 1 and 2 show a turbine wheel having a peripheral dovetail-likegroove a which is filled up by blades and distance pieces and whereinfor example the distance pieces are riveted to the groove walls .9 inthe outer portion of the groove which is not undercut at all, bytransverse rivets b and the blades are riveted through the walls of theinner dovetail portion of the groove by similar transverse rivets c. ,7

Fig. 3 shows a groove undercut at right angles and Figs. 4, 5 and 6 showunder cut grooves of dovetail sha e; in these cases the centrifugalforce of the lades is divided into two com onents, the greater componentacting radia 1y, exerts a pulling strain upon the rotor groove walls,while the smaller component acts axially and puts a bendin strain uponthose portions of the wall whic areof narrowest cross section;'therivets are for the purpose of taking up this latter or axial strain andthus preventing breaking away at the critical cross section. 1

It will be noted that in all of the figures except Fig. 5, the grooveshave a portion 1" or r, in some cases above and in others below thedovetailed portion, the walls of which groove are parallel or nearly so.Fig. 7, also shows a groove 1 having parallel walls at the bottom of thedovetail groove a to serve for the attachment of very long blades asillustrated in Figs. 7 and 8. The distance pieces are mounted in thiscase in the dovetailed portion of the groove while the roots or shanksof the blades extend beyond the dovetailed portion into the parallelwalled portion 0 of thegroove. It is advantageous in such constructionto let the radial strain be taken up by the rotor groove walls only. Inthis case the rivets are only intended to hold the rotor groove wallstogether and to secure them against breaking away. The radial depth h,Fig. 7, of the groove is not sufficient however, tofix the blades as itis .very small compared with the radial length H -of the effective bladesurface. It is for the purpose of increasing the radial depth of theholding portion of the groove that the additional annular groove 1" isturned in the bottom of the dovetail groove a and into whichthe roots ofthe blades extend. The distance pieces, for example, are riveted intothe outer or dovetailed portion of the groove by rivets b and the bladesinto the inner narrower portion of the groove,to the side walls thereofby rivets c for the purpose of securing the side walls together. Theinner narrower groove 1" is also of advantage for blades of smaller.radial depth. The distance pieces and the blades are, it is true, notall exactly equal and are therefore not equally 'well secured; ifhowever there is a groove at the base of the dovetail-like groove, intowhich the blades and distance pieces do not extend elastic lugs areformed by the side walls of the groove which, by means of the rivets,hold the blades and distance pieces firmly together. By the riveting ofthe blades it is also possible to entirely omit the distance pieces, asthe blades are already fixed by the rivets.

I claim:

1. In a turbine the combination with a rotor having an undercut groovetherein; of a comparatively long blade whose root 1S shaped to fit intosaid groove and rivets transversely through the groove and blade rootmounted therein, whereby the centrifugal force exerted on the bladeduring its rotation and the bending moments set up thereby will betransmitted to the web of the rotor.

2. In a turbine the combination with the rotor having a peripheralundercut groove therein; of two kinds of elements comprising distancepieces and blades mounted in the groove and rivets passing transverselythrough one of the kinds of elements and the groove.

3. In a turbine the combination with a rotor having a peripheralundercut groove therein; of distance pieces and blades whose shanks aremounted in the groove, and rivets passing transversely through thedistance pieces, blades, shanks and grooves.

4. In a turbine the combination with a rotor having a peripheralundercut groove therein; of blades whose shanks aremounted in the grooveand distance pieces in the groove alternating with the blades and rivetspassing transversely through the distance pieces, blade shanks andgroove, those rivets passing through the distance pieces being at adifferent radial distance from the center of the rotor, than the rivetspassing through the shanks.

5. In a turbine, the combination with a rotor having a dovetailed groovetherein; of a comparatively long blade whose root is shaped to fit .intosaid groove and rivets transversely through the groove and blade rootmounted therein, whereby the centrifugal force exerted on the bladeduring its rotation and the bending moments set up thereby will betransmitted to the web of the rotor. v

6. In a turbine the combination with a rotor having a peripheraldovetailed groove therein; of distance pieces and blades whose shanksare shaped to lit the groove, both mounted in the groove and rivetspassing transversely through the distance pieces and blade shanks, therivets passing through the distance pieces being at a different radialdis tance from the axis of the rotor than those passing through theblade roots.

7. In a turbine the combination with, a retor having a peripheralundercut groove therein and a narrower groove cut 111 the wider base ofthe undercut portion; of blades having shanks fitting said grooves andrivets passing transversely through the shanks and the narrower groove.

8. In a turbine the combination with a rotor having a peripheraldovetail groove therein and a narrower groove cut in the wider base ofthe dovetail groove; of blades having shanks extending into the narrowgroove and rivets passing transversely through the blade shanks and thenarrower groove.

9. In a turbine the combination with a retor havin a peripheral dovetailgroove therein ant a parallel walled narrower groove cut in the widerbase of the dovetail groove; of blades whose shanks fit both grooves anddistance pieces in the dovetail groove, rivets transverse to thedistance pieces, blade shanks and grooves, those rivets passing throughthe blade shanks being passed transversely through the narrow groove andthose rivets passing through the distance pieces passing transverselythrough the dovetail groove.

In testimony that I claim the foregoing as my invention, I have signedmy name in presence of two subscribing witnesses.

J OSEF KARRER.

Witnesses:

JosEPn SIMON, E. C. REDINGER.

